A California judge ruled that Starbucks and other coffee shops must put a cancer warning on coffee

As far as we know, most people aren't putting their health at risk by drinking coffee. And it may actually offer some serious benefits.Shutterstock

A California judge has ruled that businesses like Starbucks that sell coffee in the state need to warn consumers that the drink poses a cancer risk because it contains the chemical acrylamide.

Acrylamide in large quantities could be dangerous, but it's in many foods we consume — and can't be removed from coffee.

The amount in coffee is much lower than the doses shown to cause harm.

Existing research suggests coffee consumption is actually associated with lower risks for cancer and other diseases.

Coffee companies like Starbucks were fighting back against the tentative ruling, but, on May 7, a Los Angeles judge made the ruling final.

Coffee shops in California, including places such as Starbucks as well as gas stations that sell coffee, need to post labels about potential cancer-causing chemicals in coffee, a California judge has ruled.

In March, Superior Court Judge Elihu Berle issued a tentative ruling that said coffee retailers had failed to demonstrate that the threat from acrylamide was insignificant.

Coffee companies including Starbucks fought back against that decision. A group of brands including Caribou, Folgers, and Keurig issued a new court filing in April arguing that they had indeed shown that the amount of acrylamide in coffee was harmless.

The Council for Education and Research on Toxics — the group behind the lawsuit— wants to penalize companies for not warning customers that coffee contains acrylamide, a chemical that California lists as one "known to cause cancer." Companies may even have to pay fines if they don't warn customers about the risks of chemicals in coffee.

Acrylamide naturally forms when plants and grains are cooked at high temperatures. It's created in the process known as the Maillard reaction, in which high heat transforms sugars and amino acids in ways that change flavor and tend to brown food. When potatoes, bread, biscuits, or coffee are heated, acrylamide forms.

Most of the scientific evidence available indicates that consuming coffee or other cooked foods exposes humans to dangerous levels of acrylamide. Plus, as the companies pointed out in their filing, there's no known way to make coffee without acrylamide.

The roasting process is what creates acrylamide. Christopher Jue/Getty Images

Acrylamide and cancer risk

The chemical in question was first discovered by Swedish scientists in 2002, according to the American Cancer Society.

Data suggests that in large quantities acrylamide is carcinogenic to some animals. Animal studies have shown that putting acrylamide in drinking water can give rats and mice cancer. But the doses those animals consumed in the studies were 1,000 to 100,000 times the amount people get through their diet.

If you eat cooked food, acrylamide can't be avoided. It's present in about one-third of the calories that Americans and Europeans consume, on average.

According to officials at the European Food Safety Authority, "it is likely that it has been present in food since cooking began" because frying, baking, and roasting all create acrylamide. (This is the case for foods derived from plants, but not necessarily for meat or fish.)

Acrylamide does pose risks to humans, as industrial accidents when people have inhaled large quantities of it have shown. It's also one of the many chemicals produced in cigarette smoke, though that produces higher amounts than making coffee or toast does.

It's important to remember that the dose of a chemical generally determines whether it's harmful. Caffeine, which is also found in coffee, can be deadly at high doses, but that doesn't mean all caffeine is bad.

Humans also metabolize acrylamide differently than animals do and, so far, studies haven't found any harmful connection between consumption of foods containing acrylamide and various common cancers in people.

Health benefits of coffee

According to the evidence, drinking coffee isn't unhealthy.

At least one major review of studies found that the more coffee people drink, the lower their risk for liver cirrhosis or liver cancer. A review of more than 200 studies found that people who drank three or four cups of coffee a day were 19% less likely to die from cardiovascular disease. Heavy coffee drinkers have an 18% reduced risk for cancer overall, according to one large study, and some data indicates that coffee drinkers may be less likely to suffer from oral or pharyngeal cancer and advanced prostate cancer.

A number of studies have also found that coffee drinkers are less likely to suffer from Alzheimer's or dementia.

As far as the risks go, the International Agency for Research on Cancer has studied coffee and warned that extremely hot drinks may pose cancer risk if they burn the esophagus. But they've concluded that the drink itself is unlikely to cause certain cancers.

Most of the health benefits researchers found have been in observational studies, meaning we don't know that drinking coffee is responsible for the reductions in disease risk. But in most of those cases, researchers have concluded that drinking coffee probably isn't causing any harm.

In California, coffee will now be served with a cancer warning. But there's still not much reason to be concerned.

This article has been updated with the latest news on the California case.